1. Field
The invention relates to an electronic device, and more particularly, to a semiconductor memory device and an operating method thereof.
2. Discussion of Related Art
A semiconductor memory device among semiconductor devices is generally classified into a volatile memory device and a nonvolatile memory device.
The nonvolatile memory device has a relatively low write and read rate, but stored data is maintained even though a power supply is blocked. Accordingly, the nonvolatile memory device is used in order to store data which needs to be maintained regardless of the power supply. The nonvolatile memory device includes a Read Only Memory (ROM), a Mask ROM (MROM), a Programmable ROM (PROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable and Programmable ROM (EEPROM), a flash memory, a Phase-change RAM (PRAM), a Magnetic RAM (MRAM), a Resistive RAM (RRAM), a Ferroelectric RAM (FRAM), and the like. The flash memory is generally divided into a NOR type and a NAND type.
The flash memory has an advantage of the RAM that data is freely programmed and erased, and an advantage of the ROM that stored data can be maintained even though a power supply is blocked. The flash memory is widely used as a storage medium of a portable electronic device, such as a digital camera, a Personal Digital Assistant (PDA), and an MP3 player.